Which factions have you played campaigns as?

[QuintusSertorius]

Which leaves the Romans and Saba as the only available factions for u?

Pretty much, though I'm not keen on the weakness of Saba's infantry.

All that said, I have been tempted to try a Qarthadast campaign every now and then, largely because their Iberian infantry are good. I'd play it historical, losing battles and territory to Rome before my eventual destruction in 146BC.